<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Js事件</title>
</head>
<body>

<input type="button" value="点击添加" ondblclick="addCityItem()">

<ul id="city">

</ul>


<script type="text/javascript">
    function addCityItem(){
        var newTag = document.createElement("li")
        newTag.innerText = "北京";

        var parTag = document.getElementById("city");
        parTag.appendChild(newTag);
    }
</script>

</body>
</html>